(CNN) -- In latest twist in the bizarre murder of Kim Jong Un's half-brother, Malaysia says it won't release the body to North Korea without DNA from the Kim family.

Selangor Police Chief Abdul Samah Mat said without DNA from a next of kin, they won't hand over Kim Jong Nam's body or release the autopsy report which could reveal the cause of death.

Kim Jong Nam died after being attacked at Kuala Lumpur International Airport on Monday. South Korean officials claim he was poisoned.

Three people have been arrested so far in relation to Kim's murder: an Indonesian woman, a Malaysian man and another woman carrying Vietnamese identification.

Four days after the killing many questions remain unanswered. Here's what we know so far.

What happened?

Kim was on his way to catch a flight Monday morning to see his family in Macau, where he's lived since his departure from North Korea years ago.

The Chinese territory, a short ferry or helicopter ride from Hong Kong, is a popular gambling destination with mainland Chinese.

The exact details of Kim's murder are sketchy but Selangor State Criminal Investigations Department Chief Fadzil Ahmat told Reuters Kim "felt like someone grabbed or held his face from behind."

Kim felt dizzy and immediately went to an airport customer assistance counter, seeking medical help. They were concerned enough to take him to the on-premises clinic.

An ambulance was called but it came too late. Kim died on his way to hospital.

How was he killed?

No one is exactly sure how Kim died.

Initially, local media put forth reports of poison needles and deadly sprays, but it wasn't even clear whether Kim was killed or had a heart attack.

Then on Wednesday, South Korea's Lee Cheol Woo, the chairman of the country's National Assembly Intelligence Committee, publicly declared Kim had been murdered.

Lee stated the former North Korean heir had been killed with poison by "two Asian women." He didn't reveal how South Korea had discovered this or what poison had been used in the killing.

The autopsy of Kim's body might have revealed more but despite having been finished on Wednesday, no results have been released.

As of yet, Deputy Prime Minister Hamidi said no next of kin had come forward to claim the body.

Was North Korea involved?

No motive for the killing has been revealed, nor any explanation of how he was poisoned.

South Korea's Lee told lawmakers on Wednesday that North Korea killed Kim but, again, he didn't explain how he knew it.

"Pyongyang has been attempting to assassinate Kim Jong Nam for the past five years," a South Korean legislator, Lee Chul Woo, told reporters Wednesday. He didn't provide any evidence.

When asked about rumors that North Korea had been involved in Kim's death, Malaysia Deputy Prime Minister Ahmad Zahid Hamidi told a press conference Thursday it was "only speculation."

North Korea has requested Kim's body but Malaysia authorities said they wouldn't release it until investigations are complete.

Who did it?

Grainy security camera from the airport at the time of Kim's killing showed two young female suspects. One of the women is seen wearing a blue skirt and white t-shirt with "LOL" written on it.

The first woman was arrested on Wednesday morning at Kuala Lumpur International Airport, two days after the attack. She was carrying Vietnamese documents, which said her name was Doan Thi Huong and gave her age as 30.

Later that evening, 26-year-old Malaysian Muhammad Farid Bin Jalaluddin was taken into custody. Police said he was arrested to assist in their investigations.

At 2 a.m. on Thursday, Jalaluddin led investigators to his girlfriend, 25-year-old Indonesian Siti Aishah, who was then arrested on suspicion of being involved in Kim's death. No charges have been laid.

Who was Kim Jong Nam?

If things had gone differently, Kim Jong Nam could have been the leader of North Korea.

Born in 1971, he was the first son of then-North Korean leader Kim Jong Il.

His mother was one of the dictator's favored mistresses, actress Song Hye-rim, and for a while Kim Jong Nam was the most public of his father's sons.

But in 2001 he reportedly lost the elder Kim's favor when he tried to use forged documents to visit Tokyo Disneyland.

His half-brother, Kim Jong Un, was born to a different mistress, Ko Yong Hui, who was politically ambitious and enthusiastic to see her son succeed Jong Il as leader.

But author Yoji Gomi, who worte a book in 2012 called "My Father, Kim Jong Il, and Me" said Kim Jong Nam thought his younger brother wasn't fit to run the country.